The present invention relates generally to the correction of the temperature displayed by a device and, more particularly, to the correction of the displayed temperature due to the effects of heat generated by a liquid crystal display (LCD) backlighting the display.
In certain applications, including in commercial heating, ventilating and air conditioning (HVAC) systems, temperature display devices, such as for example thermostats, are employed that display the sensed temperature on a display screen. Often, the display screens are backlighted with an LCD to improve illumination. Typically, the temperature sensor is housed in the same enclosure with the display screen and the LCD backlight. The heat generated by the LCD backlighting effects the temperature within the enclosure, resulting in the temperature sensor transmitting a temperature to be displayed that is not the true temperature of the environment being monitored and serviced by the HVAC system. In HVAC applications, the displayed temperature on an LCD backlighted temperature sensing device may incorrectly reflect the true sensed temperature of the room in which the device is disposed by as much as 5 degrees F.
Further, the temperature signal from the temperature sensor is commonly transmitted not only to the display screen, but also to the HVAC system controller. Therefore, if the temperature signal received by the HVAC controller does not represent the true temperature of the environment with which the HVAC system is associated, but rather represents an incorrect temperature due to the effects of heat from the LCD backlighting, the HVAC system will overcompensate or undercompensate in response to the received temperature signal. In either case, system efficiency is decreased and the comfort of individuals within the environment associated with the HVAC system is less than optimal.